Separating tables



`SEPARATING TABLES Inn D. Russell, Sandringham, Johannesburg, Union oliYSoutl'lxAfxica, assgnor to The Denver Machinery Company (Proprietary)Limited, Johannesburg, Transvaal, Union of South Africa Fired ocr; 29,195s, ser. Ne. 110,559 :6 claims. (ci. 2091-458) This invention relatesto the separation of substances into two fractions, one of which isheavier than the other, by making use inthe main of a dierence ordifferences in specific gravities. Y

In` particular it relates to the'separation of the mineral content fromthe waste contentof ores whichV have been reduced to duid-solidmixtures,in ,which the degree of nenss-'of the solids and the proportion byweight are Suited to the particular ore involved.

Knownseparating tables employ the principle that, in 1a metallurgicalfluid-solids mixture moving over a surface,r the hea'v) fractiono'r'fractions tend -to settle on the surface while the lighter fractionorefractions VYremain in the top'lay'er and are carried over thesurface.A An example of a vseparating table is that employed in the goldmining industry, comprising a table of corduroy, over which thegold-bearing fluid-solids mixture .is run transversely Y toy The goldsettles against Y the corrugatons of the material. the nfes and isremoved by known methods. v ...llt is ,an object of the'presentinvention to provide a separating table that permits afcontinuousseparation of mineral ory minerals at a greater rate than was previouslyattainable and with a greater c iciency.

- LAccording tothe invention a separating table for metal#v lurgicalduid-solids mixtures or the like comprises two or more surfaces ribbedlongitudinally to form channels, theA walls of which are the ribs, theends of adjacent surfacesV being `separated by transverse gaps,adjustable blade means associated with and overhangi'ng the gaps.4 and 2The ends of the walls of the channels or the ends o f the extensions ofsuch walls are hereinafter referred to as the ends of the ribs. Thus,the heavier fraction or fractions pass through the adjustable openingsformed by the bases of the channels, the ends of the ribs and theleading edge of the blade. The lighter fraction or fractions flow overVY the blade means to the next surface Where further gravitation of thefraction or fractions. will take place,

The method of mounting the blade must be such that it can be moved inplanes normal and planes parallelv to the surface'of the table,vand canalso be tilted, since yfor proper operation ofthe table the `leadingedge of thev blade must alwaysbe in contact with the ends ofthe ribs.

In a modiiedform of the invention the blade is mounted at or near theleading edge of a surface with respect to the directionsv o'fjow o f theHuid-solids mixture in aY similar way tothe preferred form, and is in'contact with the bottom of those parts of the ribs which overhang thetrailing edge ofthe preceding surface, and overhangs the l gap to avariable partial extent., As in the case of the preferred form, theheavier fraction or fractions pass through the adjustable openings.which in Ithe modified form are thus formed by the leading edge of the'blade, the bases of the channels at theV trailing edge ofthepreceding.surface and pantsl of the ribs. The adjustable openings may also beformed by adjusting the blade back in the direction of iiow of thefluid-solids mixture,v and, then ladjusting it to come in contact withthe endsof the.` ribs. The method of mounting thejblade must be suchthat .it can be moved` in planes normal and planes parallelto thesurface of thetable, and can 'also be tilted.

In the majority of cases turbulence is undesirable for a successfulseparation, vand the underside 'of vtheblade is designed in such amanner to maintain :as stream lined a lilow as possible after the heavyfraction or fracf tions have `,passed through the adjustable openings.The, trailing .edge of thepreceding surface and the ends of the ribs mayalso be designed ,to maintain as streamlined a. flow as possible. .ilnthe three cases the designsV ccmtern-A plated are curvatures suflicientto create lal streamlined ,f oW. The widthjof the ribs may also be.designed in such a manneras to obviate turbulence as muchas possible.V

adapted to Contact with its leading edge the ribs Vnear the? trailingedge of the surface with respect to the direction ofthe-dow of theduid-solids mixture tofpresent-anse'ries of adjustable openings to theow of themixture.

vthe`preferred form of the invention, theA separat-ing table maycomprise acascade of ribbed surfaces along thelength of the table.I `V fY n The functions of the channels are at 'least threefold. Firstly theheavy fraction or fractions are assisted lthereby to gravitate towardsthe bases ofthe channels and s'to separate from the lighterfractions.lSecondly, they pre# vent the fluid-solids mixture, when fedv under.proper In the operation ofv timetable,k a, fluid-solids mixturecontaining the mineral-or minerals. is fed OnftO Oneend: substantiallyevenly, the table being approximately level across its width and thelongitudinal slope and degree of tion or fractions cascading beingdetermined'by `exlgeriment for ydifferent Y ores'. Y t Y v Theheavyfraction or fractions having gravitated` tof.K wards the ybases ofthe channels pass through the adjustable openings to acollectingtraywhile thelighter frac-.

`ribbed surface.' l

conditions, from flowing `to oneor otheraside `after entering the.channels,should the table not beperfectly level across its width.Thirdly, the'channelsassisttodis` tribute the'ow satisfactorily over thefull width .of the table, -and'thereby ensure as far as possible evengravitation of the heavy fraction: orfractions.' means is preferablymounted at ornearrthe leading edge of aV surface with respectfto `thedirection of flow/ofthe The blade f, i. 'Ihetablemayeither bestationary/primary lac-' "vibratedv l during the operation. .tr *YAccording ,to` the 'substance' or; substancesto Y be sepa-` rated,"l itmaybe necessary to include one or ,moreyi'otaf tion reagents,` wettingagents orrother compounds',toas:Vv

sist' in the separation'oftlie heavyv fraction or fractions. from, thelight fractionor fractions.For example, it` may. be that. d uetotheparticle sizes loff-theheavier fraction or-vfractionsL coupledwithfthe surface tensioneffecti fluid-solids mixture and ovcrhangs the`gap to a `variable,

, partial extent. The leadingedge of the 'blade'withr` v spect tothedirection of ow of the duid-solidsy mixture," which edge ishereinafter-referred tojas the'ileading edge v f l ofthe blade, comesinto contact with the'ends" ofthey l p s A v l l u Figurel 1s aperspective View of'a separatrngtable; ai".

portion .of thetable ina preferred' forni illustrating as'gap f Y' wallsVof the vchannels near `thetrailing .edge 'offa' pre:-V

ceding ysurface with respect to the direction ofthe iiowfofthe'Filuid-solids mixture, fthe latter 'edge fbeing'fhereinaiter.'referred Itoas the trailing ,edge Qf-thexpreceding :Surfaces .Y 7

theheavy,fparticles are caused -to floatlonrthe surface of`thefluidfsolids"mixtureL Thev addition, for example, of a wetting agentmayrei'novefthis diculiy;`

embodiment vof the inventionis described hereunder` y with referencev totheYaccornpanyingv drawings in which Figure 2"'is aV sectional side orlongitudinal 'View' off-a1 adjustableplate;A :y :e i

pass,v over the' blade `,tothe following l Figure 3 is a transversesection on the line 3-3 of Figure 1, and

Figure 4 is an enlarged sectional side or longitudinal view of a portionof the table in a modified form illustrating a gap and an adjustableblade.

The table is bound by walls and 11 and comprises a cascade of units, inthis case, four, each of which consists of a ilat base 12 upon which arelocated longitudinal ribs 13. Thus channels are formed by at bases 12and the ribs 13.

At the end of each unit there is a gap 14, leading to a drawing-offmeans, in this case represented by a gutter 15, along which theseparated portion may flow to collecting means. The bases 12 of thetable terminate in a curved portion 16, the curvature of which isdesigned to minimise turbulence at that point, since any turbulencewould cause mixing of the heavyy and lighter fractions. The ribs 13terminate at the gaps, and the ends of the ribs are at an angle ofapproximately 135, with a plane parallel'to the surfaces of the units.

' Referring to Figure 2, a blade 17 pivotedat 18 is provided along itslength with a number of adjusting screws 19 by which the angle of theblade in relation to the table, its height above the table and itslongitudinal position on the table may be varied, and consequently theadjustable openings formed by the bases of the channels, the ends of theribs 22 and the leading edge of the blade when in contact with the endsof the ribs may be varied for different metallurgical fluid-solidsmixtures. Adjustment of the blade in any of the directions of adjustmentmust be done in such a manner that on completion of the adjustment theleading edge of the blade is in contact with the ends of the ribs 13.

The leading edge of the blade touches the ends of the ribs 13 at points20 so that the heavy fraction or fractions pass through the adjustableopenings, while the lighter fraction or fractions pass over the-top ofthe blade to the following unit of the table, where the operation isrepeated ,until the remainder of the fluid-solids mixture passes overthe trailing end of the table with respect to the direction of ilow ofthe fluid-solids mixture.

-In order further to promote tranquility of ilow in theY neighbourhood of the blade, the under side of the blade may be curved at 21 along thelength of the blade, the radius of curvature being suitably chosen witha view lto minimising turbulence. lFor the same reason the ends of ribsmay be rounded, the radius of curvature being suitably chosen with aview to minimising turbulence.

Referring to Figure 4, a blade 17 pivoted at 18 is provided along itslength with a number of adjusting screws. 19. The head 23 of a screw 19is located within a depression 24 of the blade 17.y By tightening `orloosening` the screw. 19, the blade may be adjusted ina planesubstantially normal to the table. It will also be rseen that the screw19 is ablev to slide Within the hole 25 so that theblade 17 isadjustable in a plane parallel to the table. Since the blade 17is'pivoted `at 18, relieving the tension on bolt 19 by turning the Ynuttowards the free end thereof, will cause the ,edgeV 20 to be loweredbecause of thev disposition of the gutterrelative to the pivot 18. vObviously, when the nut is tightened on the bolt 19, the edge is movedupwardly. 'In operation the fluid-solids mixture to be concentrated ispassedon to the table substantially evenly, the tableY beingapproximately level across its width, in the direc-" tion shown inFigure 1 by the arrows A. Each blade isv set to a predetermined angle,height andlongitudinalV position according to the composition. of thehuid-solids mixture and other factorwhich may be relevant. The table issloped to a predetermined degree according to the rate 'at-which thehuid-solids mixture is to pass over thetable; l

V-For satisfactory working the bases ofthe Vchannels must, be flat andthe sides of the ribs should. be inclined slightly. x

4l Y For concentrating certain fluid-solids mixture the bases of thechannels should be of the order of one-eighth of an inch wide.

As the fluid-solids mixture flows along the channels, the difference inspecific gravity causes the heavy fraction or fractions to graviatetowards the bottoms of the channels.

The separating results have been found to be much i more satisfactorywhere instead of a gap between the leading edge of the blade and thetrailing edge of the preceding surface a number of adjustable openingsare provided for as described aforegoing.

At the trailing end of a surfacegra certain proportion of the heavy`fraction Yor, fractions is present in the lower sections of thechannels. By having' adjustable openings instead of a gap at the end ofthe preceding surface, and by making provision for maintaining asstreamlined a iiow as vpossible through the adjustable openings in themanner indicated aforegoing, such proportion of the heavy fraction orfractions is maintained as muchv as-v possible, thus ensuring that asmuch of such fraction ori fractions as possible ow through theadjustable openings.

Having collected the different fractions at the pointsv 15 lthefractions are either re-introduced on to the tablev or another table orfurther treated in some-other way.

In constructing a table according to the invention, care-l should betaken to ensure that the ribs are as as possible and at the requireddistance apart having regard to the ore mixture to be treated. 'Ihesides of the ribs should be sloped, the angle again depending on themixture of ores to be separated since the sides of the ribs assistmaterially in the separation and prevent blocking of the openings bylarge particles. Particles which have the same or greater diameter asthe width of the channels, and of the openings, will tend to ride abovethe blade. i

I claim:

1. A separating table for metallurgical fluid-solids'mixtures comprisingat least two surfaces longitudinallyr ribbed, the ends of adjacentsurfaces being separated by` transverse gaps, at each gap blade meansmounted at' the leading edge of each surface with respect to thedirection of ow of the fluid-solids mixture, means to ad-v just theblade means substantially parallel to the surface of the table, means toadjust the blade means in aplane substantially normal to the surface ofthe table and means to tilt the blade means, the blade means overhang-ving the gap and contacting the ribs at the trailing edge ofl a surfacewith respect to the direction of dow of the fluidsolids mixturetopresent a series of adjustable openings to the flow of the mixture. Y

2. The separating table as claimed in claim 1 in which the ribs overhangthe gaps to an extent whereby the ends of the ribs form, in longitudinalsection lan angle of about4 135 with a plane parallel tothe surface ofthe table.

3. The separating table as claimed in claim l in which the `trailingedge ofreach surface is shapedl topromote tranquil flow of the heavyfractions ofthe fluid-solids. mixture thereover.

4. A separating table for. metallurgical fluid-solids mixturescomprising yat least two surfaces longitudinally v ribbed, the ends ofadjacent surfaces being separated :by

transverse gaps, at each gap blade means mounted at the leading edge ofeach surface with respect to the direction of ow of the uid-solidsmixture', means to `adjust the.,y blade means substantially parallel tothe surface of the. table, means to adjust the blade'means in aplaneasubstantially normalto the surfaceof the .table and means to tiltthe.blade means, the blade means overhanging` the gap and contacting theribs at the trailing edge of aV surface with respect to theV directionofowof the uidsolids mixture to presenta series of adjustable openingsto the ow of the fluid-'solids'mixttue, the trailing edge of eachsurface being shaped to promotetranquil'ow of the heavy fractions ofthe..fluid-solids'mixtureithereover;`

and the` ribsloverhanging the'gapstozan extent ,wherebyt the ends of theribs form, in longitudinal section an angle of about 135 with `a planeparallel to thev surface of the table.

5. A separating table for metallurgical duid-solids mixtures comprisingat least two surfaces longitudinally ribbed, Kthe ends of adjacentsurfaces being separated by transverse gaps, at each gap blade meansmounted at the leading edge of each surface with respect to thedirection of flow of the Huid-solids mixture, means to adjust the blademeans substantially parallel -to the surface of the table, means toadjust the blade means in a plane substantially normal to the surface ofthe table and means to tilt the blade means, the blade means overhangingthe gap and contacting the ribs at the trailing edge of a surface withrespect to the direction of ow of the Huidsolids mixture to present aseries of adjustable openings to the ow of the duid-solids mixture, thetrailing edge 6 of each surface being shaped to promote tranquil ow ofthe heavy fractions of the fluid-solids mixture thereover and theunderside of the blade means being shaped to promote tranquil flow ofthe duid-solids mixture thereunder.

6. .The separating table as claimed in claim 5 in which the ribsoverhang the gaps to an extent whereby the ends of the ribs form, inlongitudinal section an angle of about 135 with a plane parallel to thesurface of the table.

References Cited in the file of this patent UNITED STATES PATENTS926,031 Stover June 22, 1909 2,228,607 McDonald Jan. 14, 1941 2,674,374Elliott Apr. 6, 1954 2,812,060 Hearn Nov. 5, 1957

